There are nine common types of power problems, shown in the table below. The 3-5-9 concept clarifies what types of problems can be avoided with which solutions, and in which environment each solution is the most useful.
A basic solution that protects non-critical hardware and data against three out of the nine power problems. These UPSs operate in standby mode.
An intermediate solution for office environment and servers featuring good communication options. Operating in line-interactive mode, these UPSs provide protection from the five most common power problems.
These double-conversion UPSs with excellent connectivity and communication features provide full protection against all nine types of power problems. Most of them can run in parallel, thus providing 100-% uptime in the most critical of applications.